Related Experiment Video
Updated: Jun 3, 2026
07:18
Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method
Published on: June 14, 2019
How water droplets evaporate on a superhydrophobic substrate
Hanneke Gelderblom1, Álvaro G Marín, Hrudya Nair
1Physics of Fluids, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Summary
Investigating water droplet evaporation on superhydrophobic surfaces reveals a universal evaporation behavior. Droplet mass and contact angle changes follow predictable patterns, independent of initial size or angle, for pinned contact lines.
Area of Science:
- Surface Science
- Fluid Dynamics
- Materials Science
Background:
- Evaporation of water droplets is crucial in various scientific and industrial applications.
- Previous research primarily focused on droplets with contact angles below 90 degrees.
- Superhydrophobic surfaces offer unique properties for controlling droplet behavior.
Purpose of the Study:
- To investigate water droplet evaporation on superhydrophobic substrates with pinned contact lines.
- To analyze a wide range of contact angles, from 10° to 150°.
- To compare experimental data with existing theoretical models.
Main Methods:
- Utilizing superhydrophobic carbon nanofiber substrates to achieve high contact angles and pinned contact lines.
- Experimentally measuring the time evolution of contact angle and droplet mass.
- Analyzing data against the theoretical model by Popov (2005).
Main Results:
- Experimental data align quantitatively with the Popov model.
- Evaporation is confirmed to be a quasistatic, diffusion-driven process, unaffected by thermal effects.
- Both contact angle and droplet mass evolution data collapse onto universal curves for all droplet sizes and initial contact angles.
Conclusions:
- The study validates a theoretical model for droplet evaporation on superhydrophobic surfaces.
- A universal behavior for pinned droplet evaporation is demonstrated across a broad range of conditions.
- This finding simplifies the understanding and prediction of evaporation dynamics in such systems.
More Related Videos
Related Concept Videos
01:57Adaptations that Reduce Water Loss
Though evaporation from plant leaves drives transpiration, it also results in loss of water. Because water is critical for photosynthetic reactions and other cellular processes, evolutionary pressures on plants in different environments have driven the acquisition of adaptations that reduce water loss.
01:07Cohesion
Cohesion is the attraction between molecules of the same type, such as water molecules. Water molecules have an overall neutral charge but are polar molecule. An oxygen atom in one water molecule has a partial negative charge that can bind to a hydrogen atom with a partial positive charge in a second water molecule, forming a hydrogen bond. Each water molecule can form up to four hydrogen bonds with other water molecules. Hydrogen bonds are responsible for water's cohesive nature.
On a surface,...
On a surface,...
02:57Surface Tension, Capillary Action, and Viscosity
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
01:18Vaporization
The physical form of a substance changes by changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. For vaporization to occur, kinetic energy must be greater than the intermolecular forces that keep molecules bonded. The amount of energy needed to vaporize a quantity of liquid at a given pressure and a constant temperature is called the heat of vaporization. When...
01:24Surface Tension
Surface tension is defined as the force per unit length (γ) acting along the surface of a liquid. It arises due to strong intermolecular forces of attraction. A molecule located inside the bulk of the liquid is surrounded by other molecules and experiences equal forces in all directions. However, a molecule at the surface experiences unbalanced forces because there are more neighboring molecules below than above. This creates a net inward force that pulls surface molecules toward the interior,...
01:00The Water Cycle
The Earth’s hydrosphere includes all of the areas where the storage and movement of water occurs. Since water is the basis of all living processes, the cycling of water is extremely important to ecosystem dynamics.